Superconducting nanowire single photon detector made from 4-nm-thick niobium nitride thin film on top of aluminum nitride substrate. The large meanders are integrated inductors to slow down the speed of the device. The narrow section of the nanowire (shown in inset), which consists of 60-nm-wide parallel wires, is extremely sensitive and able to respond to even single photons. Imaging was performed with Zeiss Sigma SEM.